A generic light source unit and also a generic projector are known from US 2009/0284148 A1. In this case a multiplicity of segment regions is arranged on a transparent base material which is mounted such that it can be rotated and which in particular is formed on the basis of glass or resin. In at least two of these segment regions are applied layers of different luminescent substances which emit light within a predetermined wavelength range when they are excited by excitation light. The light source unit described therein furthermore includes an excitation light source for emitting light in the visible spectrum onto the luminescent substance layers.
A disadvantage of this known light source unit consists in the fact that the average luminance which can be achieved from a luminescent substance surface is comparatively low. Light source units having higher average luminances are desired in particular for use in projection applications and in devices for fiber coupling, in particular in endoscopes.